Pinch Technology: 기본 이론

Identify Opportunities by Inspection Process Unit 10 C 100 C 150 C 30 C SteamCooling Water FeedProduct An opportunity for heat recovery Stream AStream B

Heat kW Process Unit 10 C 100 C 150 C 30 C SteamCooling Water FeedProduct Temperature C Good Idea … or is it? A B

Temperature C Heat kW Cooling Water Steam A pity ! One part of the site Another location Process Unit 10 C 100 C 150 C 30 C SteamCooling Water FeedProduct Temperature C Heat kW Not a good idea any more? A good idea ? C D B A

Temperature C But suppose we could have seen the entire picture ! Better Approach B A C D

Especially On a large site When we have different departments No one person has all the knowledge etc. How can we avoid missing such opportunities?

Do we really need 2,040 kW of steam? An Example

Heating and Cooling Duties

The hot composite curve

The cold composite curve

Energy Targets Ahead of Design! The composite curves PINCH Q cmin =120 kW Q Hmin =960kW

The composite curves show our target (minimum) should be 960 kW of steam We actually use 2040 kW Why?

The closest approach between the composite curves represents the "Pinch".

Divide the process at the Pinch

The feasibility of heat transfer

Therefore if we have ‘A’ kW of cross pinch heat transfer our utility consumption will be: Steam Q HMIN + A Cooling Water Q CMIN + A In our example the X pinch heat transfer must be 1080kW

Do not use hot utility below Do not recover process heat across Do not use cold utility above Do not Transfer heat across the Pinch

Divide the process at the pinch Pinch Design Principles

Design now achieves the target of 960 kW steam Pinch Design NEW

Design now achieves the target of 960 kW steam Pinch Design NEW SMALLER EXCHANGER AND BOILER PLANT SMALLER EXCHANGER AND COOLING TOWER

NEW SMALLER EXCHANGER AND BOILER PLANT SMALLER EXCHANGER AND COOLING TOWER Which Design Is Cheaper? To operate - clearly the one with less energy To build? The more energy efficient design is not necessarily more expensive Original Design

Q HOT T H Q COLD T H Composite Curve Grand Composite Curve Process / Utility Interface

T HH HP Steam Cooling Water HP Steam MP LP bfw CW Simple Process/Utility Interface Alternative Process/Utility Interface Process / Utility Interface